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Urinary Exam 2 > Regulation of Renal Transport > Flashcards

Regulation of Renal Transport Flashcards

1
Q

Urine pH range:

A

4.5-8.0 depending on diet

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2
Q

In what form are H+ ions secreted in the nephron?

A

Trap it in ammonia and phosphate ions

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3
Q

Early proximal convoluted tubule S1 cell H+ and HCO3- transport:

A

Apical: HCO3 -> CO2 + H2O (breaks it down CO2 and H20 diffuse across)
Basolateral: Na/HCO3- cotransporter

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4
Q

Late proximal convoluted tubule S3 cell H+ and HCO3- transport:

A

Apical: NHE and H+ ATPase pump
Basolateral: HCO3-/Cl- exchanger and Na/HCO3- cotransporter

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5
Q

TAL H+ and HCO3- transport:

A

Apical: NHE and H+ ATPase pump
Basolateral: HCO3-/Cl- exchanger

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6
Q

Alpha intercalated and medullary collecting-duct H+ and HCO3- transport:

A

Apical: NHE and H+ ATPase pump and K/H ATPase
Basolateral: Na/HCO3- cotransporter and HCO3-/Cl exchanger

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7
Q

What do alpha intercalated cells do?

A

Excrete H+ via H/K ATPase (K+ in H+ out) and H+ ATPase and reabsorb HCO3-

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8
Q

What do beta intercalated cells do?

A

Absorb H+ and secrete HCO3-

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9
Q

When urine is acidic what types of drugs tend to be reabsorbed?

A

Weak acid drugs

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10
Q

When urine is alkaline what types of drugs tend to be reabsorbed?

A

Weak basic drugs

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11
Q

What type of urine does meat cause?

A

Acidic urine

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12
Q

What food causes more basic urine?

A

Foods rich in carbohydrates

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13
Q

What affects does aldosterone have on Na+ transport?

A

Increase apical ENaC channel expression

Increase basolateral Na/K pump

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14
Q

Effect of guanylin peptides?

A

Diuresis: increase cGMP

decreased Na+ reabsorption by decreased K+, Na/K, N/H channels

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15
Q

Effect of prostaglandin/bradykinin?

A

Diuresis: decreased K+ and ENaC

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16
Q

Effects of dopamine?

A

Natriuresis: decreased NHE and Na/K

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17
Q

What is the neurohormonal gastrointestinal renal axis?

A

Fluid and solute intake in the gut cause release of gut-derived factors that affect the kidney

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18
Q

What are some neurohormones released from the gut?

A

Guanylin
Uroguanylin
Glucagon-like peptide 1 (GLP-1)

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19
Q

Agonists of guanylate cyclases in the kidney?

A

STa
GN
UGN

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20
Q

Two signaling pathways for guanylin peptides in proximal tubule?

A

GC-C: increased water secretion AQP-1 (diuresis)

cGMP dependent: decreased Na+ reabsorption (natriuresis)

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21
Q

Guanylin peptide signaling in principal cells of the CCD?

A

Activate phospholipase A2 to increase arachidonic acid concentration and inhibit Na+ channels and AQP 2, 3, 4

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22
Q

Where does dopamine cause diuresis?

A

PCT

TAL

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23
Q

PCT phosphate handling:

A

Apical: Na+/HPO4- and
H2PO4-/Na+ absorption via NaPi-IIa
Basolateral: not yet known

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24
Q

What does PTH cause?

A

Increased phosphate excretion

Decreased phosphate reabsorption

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25
Q

What does calcitonin cause?

A

Increased phosphate excretion

Decreased phosphate reabsorption

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26
Q

Two signaling pathways of PTH?

A

G-alphas: activates adenylyl cyclase -> cAMP -> PKA
G-alphaq: PLC -> PKA
both remove NaPi-IIa from apical membrane

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27
Q

ANP signaling pathway?

A

PKG activation to remove NaPi-IIa from apical membrane

28
Q

Calcium reabsorption in proximal intestine?

A

Apical: calcium channels
Basolateral: Ca++ ATPase and Na/Ca antiporter exchanger

29
Q

How are calcium intracellular levels kept under control?

A

Ca++ entering at the apical membrane will increase the microenvironments levels causing a binding of Ca++ to calbindins, as Ca++ is pumped out the basolateral membrane the microenvironment decreases in concentration causing a release of Ca++ from calbindin

30
Q

Vitamin D effect?

A

Calcium absorption

31
Q

Hepatic Vitamin D metabolism?

A

Vitamin D is carried through blood via D-binding protein to the liver and metabolized via CYP27A1 or CYP2R1 to active 25 (OH)2-vitamin D where it is filtered in kidney and picked up by apical megalin receptors

32
Q

Renal vitamin D metabolism?

A

Megalin picks up 25 (OH)2-vitamin D and converts it to active 1,25(OH)2-vitamin D shipped to target organs via DBP

33
Q

What channel is needed for Ca to be absorbed in the intestinal apical membrane?

A

TRPV6

34
Q

What does vitamin D regulate the transcription of?

A

TRPV6

PMCA

35
Q

What does calcium use to be transported out the basolateral membrane of the intestines?

A

PMCA

NCX

36
Q

Calcium channels in PCT?

A

Apical: passive Ca channel entry
Basolateral: NCX and PMCA

37
Q

TAL calcium channels?

A

Apical: passive Ca channel (TRPV6)
Basolateral: PMCA

38
Q

DCT calcium channels?

A

Apical: passive Ca channel (TRPV6)
Basolateral: NCX

39
Q

Where is calcium actively secreted in the nephron?

A

NOWHERE in the nephron

40
Q

What is the negative feedback mechanism for PTH?

A

CaSR receptors monitor serum calcium levels that cause a generation of arachidonic acid metabolites which inhibit the release of PTH and increase expression of vitamin D receptors (VDR) which increases cell’s sensitivity to negative feedback exerted by 1,25(OH)2-vitamin D

41
Q

How does PTH increase GI calcium uptake?

A

Stimulates activation of intermediate form of vitamin D to calcitriol in the kidney to uptake GI calcium

42
Q

What secretes calcitonin?

A

C cells in the thyroid

43
Q

What does calcitonin cause?

A

Osteoblast bone formation

Osteoclast decreased bone resorption

44
Q

How is Mg reabsorbed in the PCT?

A

Solvent drag paracellularly

45
Q

What is the major factor in creating the transepithelial voltage gradient in TAL?

A

NKCC

46
Q

What is needed for Mg paracellular route in the TAL?

A

Paracellin-1

47
Q

What increases Mg reabsorption TAL?

A

cAMP

PKA

48
Q

What decreases Mg reabsorption in the TAL?

A

Decreased transepithelial mV

49
Q

What channels in principal cells secrete potassium?

A

Na/K pump
K channel
K/Cl symporter

50
Q

How does acidemia cause hyperkalemia?

A

Exchanges intracellular K for extracellular H displacing K into the interstitium

51
Q

What does acidemia cause?

A

Hyperkalemia

52
Q

What does acidosis cause?

A

Decreased K+ secretion

53
Q

How does acidosis cause decreased K+ secretion?

A

Decreased basolateral Na/K pump

Decreased K channel gating and permeability

54
Q

What does alkalosis cause?

A

Increased K+ secretion

55
Q

How does alkalosis cause increased K+ secretion?

A

Increased basolateral Na/K pump
Increased K+ channel gating and permeability
Increased K/Cl symporter

56
Q

Epinephrine/catecholamine affect on K+?

A

Decreased K+ secretion: increased K+ extra-renal tissue uptake and decreased secretion

57
Q

AVP/ADH affect on K+?

A

Increased K+ secretion

58
Q

How does AVP/ADH cause increase K+ secretion?

A

Increase apical Na+ conductance depolarizing apical membrane and providing a larger driving force for K+ efflux (pushing K+ out of the cell)

59
Q

What is the most potent stimuli for K+ secretion?

A

Rate of fluid flow in the lumen; more fluid = more K+ secretion

60
Q

Why does increased flow cause increased K+ secretion?

A

Because the apical membrane of principle cells is highly K+ permeable; if flow is low then a concentration of K+ builds up in the lumen and less of a driving force exists for K+ to leave the cell; when flow is high there is a low K+ concentration bc it is constantly being swept away

61
Q

What does high HCO3- levels cause?

A

Hypokalemia levels by stimulating K+ transfer into cells

62
Q

What substances buffer hyperkalemia?

A

Insulin
Epinephrine
Aldosterone

63
Q

How do insulin, epinephrine and aldosterone buffer hyperkalemia?

A

By promoting transfer of K+ from extracellular to intracellular via Na/K pump

64
Q

What can lack of insulin or RAS cause?

A

Hyperkalemia by not allowing cells to uptake K+

65
Q

What can administering beta-adrenergic blockers cause?

A

Hyperkalemia by not allowing cells to uptake K+

Urinary Exam 2 (16 decks)

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